Automotive mirror assemblies can play a vital role in vehicle operation. Placement of the vehicle operator within the vehicle structure often makes direct line-of-sight to surrounding vehicle areas impractical. Yet such visual inspections of surrounding areas can provide the vehicle operator with information necessary for proper vehicle operation. As vehicle size increases, so often does the difficulty of accurate visual inspections. Vehicles, such as school buses, often utilize increased vehicle sizes while requiring visual inspection of areas in front of and to the side of the vehicle. To this end, it is well known that vehicle mirrors may be front-end mounted to the vehicle to provide the widest possible field of view around the vehicle.
Early attempts at widening the operator's field of view focused on the use of convex mirrors. By increasing the size of the convex minor, it was discovered that the field of view could be increased. Unfortunately, increasing the size of the convex mirror quickly becomes inefficient as the mirror itself begins to become an obstruction to forward viewing. To accommodate the need for increased field of view, without negatively impacting mirror size, it is known that a domed mirror lens may incorporate a varying radius of curvature along one of either the major or minor axis. The varying radius of curvature achieves a compacted wide field of view or viewing area within minimal space such that the driver can look forward of the vehicle with minimal blockage of vision. These mirrors with varying radius of curvature along one axis are commonly referred to as cross-over mirrors.
Although the use of cross-over mirror designs has proven highly successful in the increase of viewing area while minimizing mirror size, present designs still can incorporate drawbacks. One of the drawbacks of these common cross-over mirror designs results from the distortion of images reflected in the mirror. Image distortion can result from the depth of the dome and the varying radius of curvature of the lens. This distortion can result in a reflected image of an object that is either elongated or widened depending on the orientation of the axes of the mirror. Present designs, further limit the usefulness of such mirrors by requiring the mirror to be designed to provide either a larger image or a wider field of view.
It would, therefore, be highly desirable to have a mirror assembly that provides a combination of larger image size and wider field of view. It would further be highly desirable to have a mirror assembly that could provide such a combination of viewing benefits while minimizing distortion of images reflected in the mirror assembly.